fix(demos/ota): broadcast map -> odom continuously when robot is idle

AMCL only broadcast its map->odom TF after the robot drove
update_min_d (0.25 m) or rotated update_min_a (0.2 rad). The demo's
flow has the robot sitting still while the operator inspects the
Foxglove dashboard - so the map frame never showed up in the Display
Frame dropdown until they published a goal and the robot actually
started moving. Foxglove just sat in 'Missing transform from frame
<map>' for the whole pre-OTA narrative.

Set both update_min_d and update_min_a to 0 so AMCL broadcasts on
every laser scan. Also drops the duplicate keys that were sitting
below the original block - they were silently overriding the values
I'd just added.

Author: bburda

demos/ota_nav2_sensor_fix/ros2_packages/ota_nav2_sensor_fix_demo/config/nav2_params.yaml

@@ -49,9 +49,15 @@ amcl:
     save_pose_rate: 0.5
     sigma_hit: 0.2
     tf_broadcast: true
+    # Broadcast map -> odom on every laser update, not only after the
+    # robot has driven update_min_d / update_min_a. Demo flow has the
+    # robot sitting idle while the operator inspects the dashboard;
+    # without continuous broadcasting Foxglove can't even pick `map`
+    # in the Display Frame dropdown until the operator publishes a
+    # goal and the robot moves.
+    update_min_d: 0.0
+    update_min_a: 0.0
     transform_tolerance: 1.0
-    update_min_a: 0.2
-    update_min_d: 0.25
     z_hit: 0.5
     z_max: 0.05
     z_rand: 0.5